Resistance mounting structure



March 8, 1960 R. E. DU Bols RESISTANCE MOUNTING STRUCTURE Filed May 13, 1959 INVENTOR ATTORNEY ROBERT E. DUBOIS United States Patent O i RESISTANCE MOUNTING STRUCTURE Robert E. Du Bois, Hammond, Ind. Application May 13, 1959, Serial No. 813,006

[2 Claims. to]. ass-m This invention relates generally to electrical resistance structures and more specifically to the mounting structure for a zig-zag resistance unit.

The primary object of this invention is to provide an improved mount for a resistor grid unit which is temperature compensating in nature for preventing the warping or deformation of the grids when they become heated.

A more specific object of this invention is to provide a resistance structure in which the grid unit is freely mounted within the supporting frame to allow for expansion and contraction of the unit within the frame with variations of temperature.

A further object of this invention is to provide a novel, simple and effective bracket for freely supporting a zigzag resistor grid unit within a resistor frame.

With the foregoing and other objects in view, the invention resides in the following specification and appended claims, certain embodiments and details of construction being illustrated in the accompanying drawings in which:

Figure 1 is a fragmentary view in front elevation of a typical resistor structure to which this invention is applied;

Figure 2 is a fragmentary view in side elevation taken along the lines 2-2 of Figure 1; and

Figure 3 is a perspective view of the resistor mounting bracket of this invention.

Resistor grids expand and contract in service due to high heat conditions, and, unless the connection to the mounting frame allows for this expansion, an unnecessary strain is set up in the grids, causing warping, breakage, and possible short circuiting. The prior art has allowed for this expansion of resistor grids in several ways, such as by loosely mounting the resistor grids to the supporting means, or by loosely mounting the supporting means on the frame. This looseness permits a general deterioration and breakage of the entire resistor unit and its ceramic insulating tubes and heavy vibrational strains. The present invention provides a novel, simple and economical means for overcoming the above difiiculties encountered in the prior art.

Referring more particularly to the drawings, the grid unit generally indicated at of any suitable alloy material is employed as a typical resistance unit in my invention. It will become obvious that the size, shape or construction of the grid unit 10 is not critical to the invention. The unit 10 is illustrated as being composed of a plurality of plates 11, with each plate being connected mechanically and electrically at a terminal end to the next adjacent plate by a bridging pin 12 as by welding. In this form of construction, therefore, it becomes obvious that the interconnection of the grid plates 11 through the pins 12 at the opposite ends of alternate plates 11 forms a zig-zag resistor unit of considerable length.

The grid unit 10 is carried by any suitable frame, indicated generally at 13, the construgtign and size of which 2,928,062 Patented Mar. 8, 1960 form a laminated stack and, when secured between end members 14 and 15 by taking up on nuts 20 carried on bolts 16, the stacks folm upper and lower framing mem .bers which lend rigidity to the whole supporting struc-,

ture.

The members 18 and 19 are generally rectangular in contour and are provided with spaced openings of sufficient size to permit easy assembly of the stack of lamina tions over the insulating sleeves 17 of bolts 16. Between adjacent insulating members 19 a plurality of substantially identical resistor mounting brackets 21 are mounted in a manner similar to the mounting of the members 18 and 19 on bolts 16. The mounting bracket 21, best illustrated in Figure 3, is preferably formed by a stamping procedure from a piece of sheet metal. Each such bracket 21 includes a planar portion 22 including a pair of spaced openings 23 and 24 to facilitate the mounting on the bolts 16. Each bracket 21 is further provided with a plurality of upstanding fingers 25. The end fingers 26 and 27 are coplanar with the portion 22 of the bracket. The intermediate fingers 28 and 29 are alternately and oppositely offset outwardly and upwardly from their integral joint with the portion22 of the bracket 21. The transverse spacing between the upwardly extending portions of the fingers 28 and 29 is predetermined to accommodate, in a sliding friction fit relationship, the combined thickness dimension of one portion of grid unit 10, including the thickness of two plates 11 and one bridging pin 12, as is clearly illustrated in Figure 1. The entire resistor structure is so designed that the longitudinal dimension of one plate plus the portion of each pin 12, connected to either side of the plate and extending slightly beyond the end thereof, is less than the distance between the outwardly extending portions of the fingers 28 and 29 of opposed brackets 21 mounted in the structure. In other words, the portion of the grid loincluding the plates 11 and pin 12 is freely mounted in light friction sliding relationship on the inner surfaces of the upwardly extending or straight portions of the fingers 28 and 29 of each pair of opposed brackets 21 in the resistor structure. The coplanar fingers 26 and 27 of each bracket 21 prevent extended transverse movement of the various plates 16 as viewed in Figure 2 by providing positive abutments for bridging pins 12.

It will now therefore be obvious to one skilled in the art that the invention provides a positive and secure means of retaining a resistor within a mounting frame while permitting adequate clearances to allow for expansion and contraction of the grid plates 16 longitudinally of themselves, to avoid warping or breakage which would occur in fixed connections. The fingers 28 and 29 of the brackets 21 contact the end portions of the plates in the manner of light spring clips, exerting enough pressure on the plates to prevent excess vibration of the grid while permitting the expansion and contraction of the grid under varying temperature conditions of the service in which the structure is used.

It is obvious that details of the structure might be readily modified and remain within the concepts of this invention and the scope of the appended claims.

I claim:

1. An electrical resistance structure comprising a pair of end members, a pair of laminated resistor grid supporting members connected between said end members to form a frame, said members each including a plurality of spacer and insulating members bound into a rigid form by bolts extending therethrough and through the end members, a zig-zag resistor grid unit, said grid unit including a plurality of plate like members joined togather at their alternate terminal ends to form a continuous resistor grid, a plurality of brackets, each bracket havinga' planar portion secured between the insulator members of a laminated end member, a plurality of fingers extending inwardly of the frame and adapted to receive and support the terminal ends of the plate-like grid members in a sliding relationship, and end fingers coextensive with the planar portion of the bracket to act as abutments and eliectively preclude any substantial transverse movement of the grid unit relative to the frame.

2. An electrical resistance structure comprising a pair of end members, a pair of resistor grid supporting members connected between said end members to forni a frame, a plurality of brackets secured to each grid supc earance 5i. i porting member, a resistor grid unit of zig-zag form, the resistor grid thereof including a plurality of plates alternately connected at oppositeends to form a continuous resistance, said brackets each including a plurality of alternately onset fingers extending inwardly of the frame which are adapted to receive and support the ends of one pair of adjacent plates of the :grid in a sliding relationship, and end fingers on opposite sides of the ofiset fingers to act as abutments and effectively preclude any substantial transverse movement of the grid unit relative to the frame.

References Cited in the file of this patent UNITED STATES PATENTS 2,059,349 Hertner Nov. 3, 1936 2,721,920 Weide Oct. 25, 1955 2,858,462 Griffes Oct. 28, 1958 

